Perl5 リファレンス

       msgctl ID,CMD,ARG
               Calls the System V IPC function msgctl(2).  You'll
               probably have to say

                   use IPC::SysV;

               first to get the correct constant definitions.  If
               CMD is `IPC_STAT', then ARG must be a variable
               which will hold the returned `msqid_ds' structure.
               Returns like `ioctl': the undefined value for
               error, `"0 but true"' for zero, or the actual
               return value otherwise.  See also `IPC::SysV' and
               `IPC::Semaphore' documentation.